Barrier seal with self regualting buffer

ABSTRACT

This specification discloses a barrier seal in which the pressure of the fluid being sealed is opposed by the flow rate of a buffer fluid with a movable ring interposed between the two. This ring is movable axially under the influence of the differential which obtains between the pressures of the sealing fluid and buffer fluid. Appropriate passages are provided for the buffer fluid and seals are provided between the movable ring and the shaft and housing in which the barrier seal is installed.

United States Patent I UN Inventor Heinz K. Muller Neustadt, GermanyAppl. No. 728,950 Filed May 14, I968 Patented Jan. 19, 1971 AssigneeSealol, Inc.

Warwick, R.I. a corporation of Delaware Priority June 3, 1967 GermanyM74257 BARRIER SEAL WITH SELF REGULATING BUFFER 5 Claims, 4 DrawingFigs.

US. Cl 277/27, 277/74, 277/91 Int. Cl Fl6j 15/40, F161 17/02 Field ofSearch 277/27, 3, 28, 74, 91

[56] References Cited UNITED STATES PATENTS 2,928,685 3/1960 Tracy277/74X 2,930,636 3/1960 Tracy 277/27 3,026,112 3/1962 Mayer 277/33,447,809 6/1969 Marrujo et a1 277/27 FOREIGN PATENTS 891,419 3/1962Great Britain 277/27 Primary Examiner-Samuel G. Rothberg AttorneyWilliamFrederick Werner ABSTRACT: This specification discloses a barrier sealin which the pressure of the fluid being sealed is opposed by the flowrate of a buffer fluid with a movable ring interposed between the two.This ring is movable axially under the influence of the differentialwhich obtains between the pressures of the sealing fluid and bufferfluid. Appropriate passages are provided for the buffer fluid and sealsare provided between the movable ring and the shaft and housing in whichthe barrier seal is installed.

PATENTEDJANIQIHYI 3556538 SHEET 1 OF 2 HEINZ K. MULLER INVENTOR ATTORNEYPATENTED JAN 1919?:

SHEET 2 OF 2 j INVENTOR HEINZ K. MULLER ATTORNEY BARRIER SEAL WITH SELFREGULATING BUFFER The present invention relates to the barrier sealscommonly employed in conjunction with a rotary shaft to provide for thesealing of a fluid under high-pressure and is concerned primarily with aseal of this type in which the rate of flow of a buffer fluid opposes orcounteracts the pressure of the fluid being sealed.

Attempt has been made to provide a barrier seal which functions on thisgeneral principle but such known devices may be characterized by thedivision of the space containing the buffer fluid into two chambers by athrottling element. This relieves the contact seal on the low pressureside from a high differential but requires external control equipmentfor the throttling element. Such supplementary equipment is undesirableboth from the aspect of cost and the possibility of becoming out oforder.

With these conditions in mind the invention has, as an object, theprovision of a barrier seal for a rotary shaft mounted in a housing witha high-pressure sealing fluid between the two, the barrier sealincluding an axially movable ring which cooperates with the housing todefine a chamber for a buffer fluid. This buffer fluid is supplied tothe chamber under a constant flow rate and the latter pressure opposesor counteracts the pressure of the sealing fluid so that the position ofthe ring is determined by the differential obtaining between the twopressures.

Another object is to provide, in a barrier seal of the type aforesaid, amovable ring of L-shaped cross section. One arm of the L in the form ofa sleeve presents an inner cylindrical surface which engages the shaft,or an annulus carried thereby, and an outer cylindrical surface whichtogether with an outer radial face on the other arm of the L, in theform of an end flange, are engaged by the buffer fluid.

Another object is to provide, in a barrier seal of the character noted,a contact seal for the inner cylindrical surface of the ring and asecond contact seal for the face of the end flange which presents theradial face. These contact seals contain the high-pressure fluid.

It is important to provide for the introduction of the buffer fluid tothe chamber where it is effective. Thus another object is to provide, ina barrier seal of the type noted, a housing having an inlet passage forthe buffer fluid and an outlet passage for relieving buffer fluid fromthechamber.

In some instances it may be desirable to provide what is in effect aclosed buffer fluid'chamber on one side of the radial face aforesaid. Insuch a case a contact seal is provided between the housing and outercylindrical surface that extends over the end flange.

In lieu of the contact seals for the face and outer cylindrical surfaceadjacent to the radial face it may be desirable to provide contact sealswhich engage the radial face at different radial distances. Thus anotherobject is to provide, in a barrier seal of the kind aforesaid, a pair ofcoaxial contact seals that are carried by the housing and engage theradial face under spring pressure.

In the latter form of the invention the inlet for'buffer fluid isadjacent to the innermost of the sealing rings. If the fluid is under ahigh rate of flow, it will impinge against the outermost contact sealingring with an undesirably high rate of flow. To prevent this the movablering is provided with a baffle which projects into the buffer fluidchamber within the outermost sealing ring.

There may be occasions when it will be desirable to provide mechanicalmeans which affect .or control the differential between the pressure ofthe 'seali ng and buffer fluids. Thus another object is to provide in abarrier seal of the type noted, spring means for urging the movable ringaxially in a direction enlarging the space which receives the sealingfluid.

Various other more detailed objects and advantages of the invention suchas arise in connection with carrying out the above noted ideas in apractical embodiment will, in part become apparent, and in part behereinafter'stated as the description of the invention proceeds.

For a full and more complete understanding of the invention referencemay be had to the following description and accompanying drawingswherein:

FIG. 1 is a fragmentary section through a portion ofa shaft and housingwith the barrier seal of this invention included therein.

FIG. 2 is a view similar to FIG. 1 of a slightly modified form.

FIG. 3 is another fragmentary section of still another modification.

FIG. 4 is a more complete section of another embodiment.

Referring now to the drawings. and first more particularly to FIG. 1, ashaft 10 is shown as journaled in a housing 11 with the spacebetween thetwo shown as exaggerated at 12. The shaft 10 has an enlarged portion 13presenting a cylindrical surface 14 and a radial end face 15. The latteris spaced from a flat end face 16 on the housing 11 to provide a space17 that communicates with the space 12.

The sealing fluid which ordinarily is under high-pressure occupies thespaces 12 and 17. This pressure fluid in indicated at The cylindricalsurface 14 is formed with an annular groove 19 closely adjacent to theend face 15. Received in the groove 19 is a contact seal 20 which maytake the form of the O-ring illustrated and is of elastic material. Thehousing 11 is formed with a cylindrical surface 21 that extends inwardlyfrom the end face 16. Formed in the surface 21 is an annular groove 22which receives a contact seal 23 which also may be an O-ring.

A movable ring is identified in its entirety by the reference characterL. It is of L cross section and comprises a sleeve 24 and an end flange25. The sleeve 24 presents an inner cylindrical surface 26 engaged bythe contact seal 20. The flange 25 has a face 27 engaged by the contactseal 23. The ring L is axially movable along the surface 21 of housing 1l and surface of 14 of shaft enlargement 13.

The flange 25 of ring L has a radial face 28 and opposite to the latterthe housing 1 1 is formed with a face 29 that is inclined relative tothe face 28 and cooperates therewith to define a conical chamber 30having a large inlet end at 31 and a narrow outlet at 32.

An inlet passage for buffer fluid is shown at 33 as formed in thehousing 11 and connecting with the larger end 31 of chamber 30. Thehousing 11 also provides a space 34 about shaft enlargement 13 and ringL. The chamber 30 communicates with this space 34 by way of therestricted outlet 32.

It will be understood that pressure of fluid 18 will tend to urge thering L to the right (speaking with reference to the showing of FIG. 1),that is away from the shaft enlargement 13. At the same time bufferfluid is introduced under a constant rate of flow through passage 33 tochamber 30. It is effective against the face 28 of ring L to tend tomove the ring L to the left, thus opposing the pressure of the fluid 18.Thus the ring L is moved by the differential which obtains between thetwo pressures until it assumes a position in which it is balanced. Anychange in the pressure of either fluid is accommodated by a shifting ofthe ring L.

Referring now more particularly to FIG. 2, the modified embodimenttherein illustrated will be described. Parts corresponding to the sameparts depicted in FIG. I bear the same reference characters.

It will be noted that the housing 11 is formed with an annular surface35 which is, in turn, formed with an annular groove 36. A contact seal37 is received in the groove 36 and engages an outer cylindrical surface38 on the ring L.

The housing 11 is formed with a recess 39 which communicates with thechamber 30 by way of the restricted outlet 32. An outlet passage 40connects with this recess 39. Obviously buffer fluid under pressure issupplied to chamber 30 and recess 39 by the inlet passage 33. It isexhausted by the outlet passage 40.

FIG. 3 illustrates a modification in which contact seals carried by thehousing engage the radial face 28 of the ring L. The housing ll has aface 41 that is spaced from and substantially parallel to the face 28.These faces 28 and 41 cooperate with contact seals 42 and 43 to define abuffer fluid pressure chamber 44. An inlet passage 45 communicates withthe chamber 44 as does an outlet passage 46.

Entering into the housing 11 from the face 41 are two annular grooves 47and 48. The sealing ring 42 is received in the groove 47 and the sealingring 43 in the groove 48. Expansion coil springs 49 are interposedbetween the bottom of each of the grooves 47 and-48 and the ring 42, 43that is received therein. These springs 49 urge the seals 42 and 43 intoengagement with the surface 28.

With this arrangement it is necessary that the ring L be properlypositioned relative to the shaft 10. Thus pins 50 are shown as carriedby the shaft enlargement 13 and projecting from the face 15. The flange25 of ring L is formed with a series of recesses 51 which looselyreceivethe pins 50 to correlate the ring L to shaft 10.

FIG. 4 discloses two additional features that are included in a furthermodification. The face 28 of ring L is formed with an annular recess 52which receives a ring 53 having an inwardly opening conical face 54. Thering 53 projects into the chamber 44 whereby the conical face 54 acts asa baffle to reduce the impinging force of the buffer fluid stream priorto engagement with the sealing ring 42. v

The housing 11 is shown as carrying an end casing 55. The latter extendsover and beyond the ring L and carried therewith is a retaining ring 56.The end face 57 of ring L remote from the face 28 is formed with acounterbore 58. An expansion spring 59 is received in this counterboreand bears against the bottom of the latter and the retaining ring 56.This spring 59 tends to move the ring L to the right (speaking withreference to the showing of FIG. 4) and thus enlarge the space 17 whichreceives the pressure fluid 18. This inhibits the crea tion of too greata differential between the pressure of the buffer fluid and the sealingfluid.

The cylindrical surface 26 of the sleeve 24 which constitutes the outerwall of the space 17 has a radius a which is slightly greater than theradius of the shaft enlargement 13. The chamber 44 of FIGS. 3 and 4 hasan inner cylindrical surface defined by radius b which is appreciablyless than radius a and an outer cylindrical wall determined by a radiusc which is greater than the radius a.

The buffer fluid is preferably cooled and acts as a cooling medium foreither of the contact seals 23 or 43.

While preferred specific embodiments of the invention are hereinbeforeset forth it is to be clearly understood that the invention is not to belimited to the exact constructions, mechanisms and devices illustratedand described because various modifications of these details may beprovided in putting the invention into practice within the purview ofthe appended claims.

lclaim:

l. in a barrier seal, a rotary, shaft having an enlarged end portionpresenting a radial face and a cylindrical surface, a housi'ng receivingsaid shaft and having an end surface spaced from said radial face andproviding a space about said shaft enlarge ment; a movable ring ofLshapcd cross section comprising a sleeve and an end flange, said sleevereceiving said shaft enlargement and axially movable thereon with saidend flange positioned in the space between said radial face and endsurface, one face of said flange being spaced from said radial face toprovide a space receiving sealing fluid under pressure. the other faceof said flange being spaced from the end surface of said housing toprovide a chamber receiving buffer fluid at a constant flow rate, saidchamber communicating with the housing space about the shaftenlargement, an inlet passage sealin fluid space between said end flangeand radial face.

3. e barrier seal of claim 1 in which said chamber is conical presentinga large inlet end and a restricted outlet communicating with saidhousing space.

4. The barrier seal of claim 1 in which said contact seals are ofelastic material.

5. The barrier seal of claim 1 in which the end surface of the housingis inclined to the radius of said shaft to define with the adjacent endface of said flange a conical chamber.

1. In a barrier seal, a rotary shaft having an enlarged end portionpresenting a radial face and a cylindrical surface, a housing receivingsaid shaft and having an end surface spaced from said radial face andproviding a space about said shaft enlargement; a movable ring ofL-shaped cross section comprising a sleeve and an end flange, saidsleeve receiving said shaft enlargement and axially movable thereon withsaid end flange positioned in the space between said radial face and endsurface, one face of said flange being spaced from said radial face toprovide a space receiving sealing fluid under pressure, the other faceof said flange being spaced from the end surface of said housing toprovide a chamber receiving buffer fluid at a constant flow rate, saidchamber communicating with the housing space about the shaftenlargement, an inlet passage for buffer fluid communicating with saidchamber, a contact seal between said sleeve and shaft enlargement, and acontact seal between said end flange and said housing, said ring beingaxially movable under the influence of the differential in pressures ofsaid sealing and buffer fluids.
 2. The barrier seal of claim 1 in whichthere is a narrow space between said shaft housing and which spacecontains sealing fluid under pressure and in communication with thesealing fluid space between said end flange and radial face.
 3. Thebarrier seal of claim 1 in which said chamber is conical presenting alarge inlet end and a restricted outlet communicating with said housingspace.
 4. The barrier seal of claim 1 in which said contact seals are ofelastic material.
 5. The barrier seal of claim 1 in which the endsurface of the housing is inclined to the radius of said shaft to definewith the adjacent end face of said flange a conical chamber.